Webster: A condition in which body health is impaired, a departure from a state of health, an alteration of the human body intercepting the performance of vital functions.
Oxford English Dictionary: A condition of the body or some part or organ of the body in which its functions are disrupted or deranged.
Ecological point of view: Disease is defined as maladjustment of the human organism to the environment.
Sociological point of view: Disease is considered a social phenomenon, occurring in all societies and defined and fought in terms of the particular cultural forces prevalent in the society.
Simplest definition is ‘Disease is opposite of health. Any deviation from normal functioning or state of complete physical or mental well being.
WHO has not defined disease as it has many spectrum or shades ranging from subclinical cases to severe manifest illness.
- Some diseases are acute-food poisoning
- Some are insidious-mental illness
- Some diseases have short course some have long course.
It is easy to determine the illness if signs and symptoms appear. If the signs and symptoms are between normal and abnormal i.e., borderline signs or symptoms are found it is difficult to determine the disease
E.g. Diabetes, hypertension, and mental illness-the symptomless disorders.
End point of the disease can be of 3 types
- Complete recovery
- Death of the host
The terms disease, illness and sickness are used synonymously
Disease: Literally means uneasiness, when something is wrong with bodily functions Disease is a physiological or psychological dysfunction.
Illness: Refers to presence of a specific disease, it includes individual’s perception and behavior in response to the disease as well as impact of the disease on psychosocial environment. Illness is a subjective state of a person who feels aware of not being well.
Sickness: Refers to a state of social dysfunction.